1. Field of the Invention
The present invention generally relates to a programmable formatting apparatus for providing information formatting of data. More particularly, the present invention relates to a programmable formatting apparatus which functions in response to a set of programmable commands to independently control field arrangements, size and content of an information format for digital data.
2. Description of the Related Art
Information that is to be conveyed in an intelligent manner is usually packaged in some agreed upon format which facilitates the transmission and receipt of the information in an intelligent form. The format may be nothing more than the layout of printed material on a page or it may be as complex as the information format provided for the new digital audio tape, RDAT.
A good example of the purpose and arrangement of such information formatting is provided by television picture information which is organized before transmission into a series of odd and even lines which then have synchronization signals added. The signals inform the receiver when a horizontal line begins and ends as well as when a new frame begins. Without these added signals, a receiver would have no way of knowing how to reassemble the picture.
In order to transmit data using a digital channel, it is necessary to attach information for synchronization, registration and identification. Specifically, a transmitter for sending digital information through a channel takes in a string of message bits from a source and produces a string of channel bits that are configured to obtain the best performance possible from the proposed channel with its inherent constraints. The difference between the message bit string and the channel bit string is control information that provides the synchronization, registration or alignment, and identification information. These tasks, and others, are accommodated by the attachment of special regions to the message data. The composite structure, i.e., the information format, can, therefore, be expressed as the catenation of fields, each of which has length and contents designed for message data or one of the supporting tasks.
Information formatting is also required in order to record data, and thus, most recording methods require certain formatting to be done. As with the television signal formatting noted above, this recording formatting involves the addition of information and special characteristics to the data during recording in order to make the read process, i.e., playback, successful.
FIG. 1 illustrates the format requirements for a particular magnetic recording device known in the field of data recording. Many different format arrangements are currently used, each of these different formatting arrangements varying in accordance with the particular needs and requirements of the specific application.
Typically, the formatting of data to be recorded is performed by dedicated formatting hardware which formats the data to be recorded in a predetermined format only. As a result, different types of formatting hardware are required to provide the formats.
While hardware is known that can maintain a particular arrangement of format fields, whose size and contents can be changed by programmable values, this type of hardware cannot change the format arrangement Since it is necessary to attach information to data for transmission, and this task imposes a format on data which varies greatly among applications, it is desirable during research and product development to have flexibility in formatting information. Thus, there is a need for formatting hardware that can format data in different ways to eliminate the requirement of purchasing dedicated hardware for each different type of information format.